Balanced multistage centrifugal pump



June 6, 1933. A. HOLLANDER BALANCED MULTISTAGE CENTRI-FUGAL PUMP FiledMay 7, 1928 Patented June 6 1933 UNITED STATES PATENT OFFICE ALADARHOLLANDER, OF. BERKELEY, CALIFORNIA, ASSIGNOR, BY MESNE ASSJIGN- MENTS,TO BYRON JACKSON 00., A CORPORATION OF DELAWARE BALANCED MULTISTAGECENTRIFUGAL PUMP Application filed May 7, 1928. Serial No. 275,796:

My invention has for its object the substantially perfect balancing of amultistage centrifugal pump as regards the axial thrust by Waterpressure on the unbalanced portions ofthe rotors.

A further object is in a multistage centrifugal pump the maintenance ofa relativel low velocity during the flow through the first pressurestage impeller thereby preventing vapor formation at the impeller inletor in the suction column.

Another object is a multistage pump which is maintained in perfectbalance yet wherein the highest pressure to which any stuffing gland isexposed is the pressure of the first stage.

Where relatively high velocities are employed on the suction side ofcentrifugal pumps or where the pump is placed ata considerable heightabove the surface of the water being pumped occasioning a relativelyhigh degree of vacuum on the suction side of the pump, the pumpfrequently becomes what is called vapor bound; in such case thecontinuity of the fluid column is destroyed and the pump ceases tofunction.

In the pump of my invention I prevent such deleterious results byemploying relatively largeareas and therefore low velocity throughoutthe first stage of pumping, after which the water delivered from thefirst stage, being now under material pressure, may be increased invelocity through the subsequent pump stages.

A further object of this invention is to provide a multistage pump witha double suction first, stage impeller, whereby even though the pump beoperated at relatively high speeds it is possible to maintain arelatively low velocity of fluid therethrough, thus preventing vaporformation at the impeller inlet or in the suction column andconsequently preventing the pump from becom ing vapor-bound. Thisfeature is especially important when the pump is utilized for handlinghot boiler feed water or casing head gasoline, which volatilize veryeasily at normal room temperature, especially at reduced pressures.

By referring to the accompanying drawing the invention will be madeclear.

The figure is a vertical cross section through the shaft axis of amultistage centrifugal pump employing my invention.

A main shaft is shown by the numeral 1 on which are mounted a pluralityof impellers forming with the shaft the rotating element of the pumpcarried in the bearings 2, 3, and provided with conventional glands 4,5, respectively;

A main body casing is shown at 6 to which is bolted the upper portion 7which forms with a body casingthe intricate volute for the severalstages.-

A suction inlet is shown at 8 and a pressure dischar e outlet at 9.

The h rst stage impeller shown at 1.0 is of the double suction typewithdrawing water from the section 8 both from the right and the left ofthe figure and discharging the same into the volute passage 11.

From the passage 11 water is delivered from the left and to the suctionside of the impeller 12 which raises the water to the second pressurestage delivering the same through the volute passage 13 thence to thesuction side on the right of the impeller 14.

This in turn delivers the water pumped to the third pressure stage intothe volute passage 15 which in turn delivers the waterto the suctionside on the right of impeller 16 which in turn raises the water to thefourth pressure stage delivering it through the volute passage 17 fromwhence it enters from the left the suction side of impeller 18 whichdelivers the water pumped to the fifth pressure stage through the volutedelivery passage 9.

The impellers are preferably of substantially the same diameter.

Conventional closures between the several stages are provided andit'will be notedthat the glands 4 and are exposed only to the firststage of pressure and the suction of the impeller only; that theleakages between.

the several impellers are confined to differences of one stage ofpressure and are therefore a minimum; that the impeller 10 being of thedouble suction type therefore provide a very much greater area-in thiscase at least twice the area of inlet as are the other impellers andthat therefore the velocity of flow of fluid into the first impeller issubstantially one-half of the velocity of flow into the suction side ofthe several other impellers or any of them and that only after the wateris actually flowing through the impeller is its velocity increased.

The maintenance of a low suction velocity prevents the pump becomingvapor bound and losing its suction.

The impeller'10 is in perfect hydraulic balance receiving equalpressures and velocity on equal and opposite areas and delivering thesame in a peripheral direction.

The impellers 12 and 14 are perfectly balanced, their areas being equaland opposite as regards direction of presure.

The same is also true of impellers 16 and 18. The pump thereforepresents a perfectly hydraulic balanced rotating element with minimumpressures at the glands 4 and 5 and with no greater than one stage ofpumping pressure difference between any two compartmentsor'adjacentimpellers.

I claim:

1. A substantially balanced multistage centrifugal pump comprising anodd number of impellers, the first of said impellers being of the doublesuction type and the others of the single suction type. said doublesuction impeller having a greater capacl y than any one of said singlesuction impellers, a means to direct a liquid stream Into the oppositeends of the double suction type of impeller. a means to direct liquiddischarged by the double suction type impeller in one direction into oneend of one of the single suction type impellers, and a means to directliquid discharged by the last mentioned impeller into one end of anotherof the single suction type of impeller in a direction opposite to thefirst mentioned direction.

2. A substantially balanced multistage centrifugal pump including acasing. a shaft rotatably mounted therein. a first stage double suctionimpeller mounted on the shaft near one end of the casing, an even numberof single suction impellers mounted back to back on the shaft betweenthe first impeller and the other end of the casing. said double suctionimpeller having a greater capacity than any one of said single suctionimpellers. and a passageway directing the fluid stream into the opposedsuction inlet eyes of the first stage double suction impeller anddirecting the fluid stream discharged from the periphery thereof throughthe single stage impellers in series.

3. A balanced multistage centrifugal pump comprising an odd number ofimpellers, the first stage of said impellers being maining singlesuction type impellers receiving the hydraulic thrust in the oppositedirection.

4. A- multistage centrifugal pump including the combination of a casing,a shaft r0 1 tatably mounted in the casing, a first stage double suctiontype impeller mounted on the shaft. an even number of single suctiontype impellers mounted on the shaft so that the entrance end of one halfthe number of single type impellers face toward one end of said casingand so that the entrance end of the remaining single suction typeimpellers face in the opposite direction, and said double suctionimpeller having a greater capacity than any one of said single suctionimpellers, and means forming a liquid passage arranged to direct aliquid stream into the 0pposed inlet eyes of the first stage impellerand for directing the liquid discharged therefrom through the otherimpellers in series.

5. A multistage centrifugal pump including the combination of a casing.a shaft rotatably mounted in the casing. a first stage double suctiontype impeller mounted on the shaft adjacentone end of said casing, asecond stage single type impeller mounted on the shaft adjacent theopposite end of the casing and having its inlet end directed toward saidopposite end, a third stage single type impeller mounted on the shaftadjacent said second stage impeller and having its inlet end directedtoward said one end of the casing, a fourth stage single type impellermounted on the shaft adjacent said first stage double impeller andhaving its inlet end directed toward said one end of the easing, a fifthstage single type impeller mounted on the shaft intermediate said thirdand fourth stage impellers and having its inlet end directed toward saidopposite end of the casing said double suction impeller having a greatercapacity than any one of said single suction impellers. a means todirect a liquid stream into opposite inlet ends of the first stagedouble suction type impellers, and a means forming a passage connectingthe impellers in series.

6. A multistage centrifugal pump includ ing the combination of a casing.a shaft rotatably mounted in the casing. a first stage double suctiontype impeller mounted n the shaft adjacent one end of said casing. asecond stage single type impeller mounted on the shaft adjacent theopposite end of the casing and having its inlet end directed toward saidopposite end, a third stage single type impeller mounted on the shaftadjacent said second stage impeller and having its inlet end directedtoward said one end of the casing, said double suction impeller having agreater capacity than any one of said single suction impellers, a meansto direct a liquid stream into opposite inlet ends of the first stagedouble suction type impeller, and a means forming a passage connectingthe impellers in series.

7. A substantially balanced multistage centrifugal pump including acasing, a shaft rotatably mounted in the casing, a first stage doublesuction impeller mounted on the shaft, a pair of single suctionimpellers mounted back to back on said shaft, the inlet area of thedouble suction impeller being greater than the inlet area of the secondstage impeller, a liquid passage connecting the discharge of the firststage to the inlet of the second stage, and'a liquid passage connectingthe discharge of the second stage with the inlet of the third stage.

8. A substantially balanced multistage centrifugal pump including acasing, a shaft rotatably mounted in the casing, a first stage doublesuction impeller mounted on said shaft, a plurality of pairs of singlesuction impellers mounted back to back on said shaft, the inlet area ofthe double suction impeller being greater than the inlet area of saidsecond stage impeller, a first fluid passage connecting the discharge ofthe first stage to the inlet of the second stage, a second fluid passageconnecting the discharge of the second stage to the inlet of the thirdstage, a third fluid passage connecting the discharge of the third stageto the inlet of the fourth stage, a fourth fluid passage connect ing thedischarge of the fourth stage to the inlet of the last stage, and adischarge passage for said last stage.

9. A substantially balanced multistage centrifugal pump including acasing, a shaft rotatably mounted in the casing and extendingtherethrough, bearings at each end of the shaft external to the casing,stufling boxes between the casing and shaft adjacent each end thereof, afirst stage double suction impeller mounted on said shaft at the inletend of the pump casing and adjacent one of said stufling boxes, a pairof single suction impellers mounted back to back on the shaft, saiddouble suction impeller having a greatoer capacity than any one of saidsingle suction impellers, and means for directing a fluid stream intothe opposed suction inlet eyes of the first stage double suctionimpeller and for directing the fluid discharged therefrom through thesingle suction impeller farthest from the first stage double suctionimpeller and then through the other of said single suction impellers.

10. A multistage centrifugal pump including the combination of a casing,a shaft rotatably mounted in the casing and extending therethrough,bearings at each end of the shaft external to the casing, stufling boxesbetween the casing and shaft adjacent each end thereof, a double suctionimpeller mounted on said shaft at the inlet to the pump and adjacent oneof said stufling boxes, a plurality of pairs of single suction impellersmounted back to back on said shaft, said \double suction impeller havingan inlet area greater than the inlet area of any one of said singlesuction impellers, a liquid passage leading from the periphery of saiddouble suction impeller to the eye of the single suction impellerfurthest from said double suction impeller and adjacent to the otherstuffing box, a fluid passage connecting the pe- 'riphery of said firstsingle suction impeller with the eye of the adjacent single suctionimpeller, and fluid passages connecting the last named impeller with thesubsequent pairs of impellers in like manner.

ALADAR HOLLANDER.

